Question

Explain refraction of light by Huygens wave theory, when waves enter from denser to rarer medium.

Hint:

When light travels to a rarer medium, it bends away from the normal.

Answer 1

According to Huygens' wave theory: \begin{itemize} \item Each point on a wavefront acts as a secondary source of wavelets. \item When light travels from a denser to a rarer medium, the speed of the wave increases. \item The wavefront bends away from the normal due to the increase in speed. \end{itemize} The refractive index is given by: \[ n = \frac{\text{speed in rarer medium}}{\text{speed in denser medium}} \] \[ \boxed{\sin i = n \sin r} \]